Lightning strikes from electrical storms are a serious threat to all types of electrical equipment. A nearby lightning strike can burn out circuits in an electrical device such that repair is impossible and replacement is the only alternative. Other electrical disturbances, such as short circuits or electrical arcing between a pair of conductors are an equally serious threat to electrical equipment. While there are various types of surge and spike protectors on the market, these are not designed to protect against the extreme conditions present during a lightning strike or the electrical disturbance caused by arcing between a pair of conductors.
The inventor herein provided an improved apparatus for unplugging various electrical equipment, as discussed in U.S. Pat. No. 5,083,042. The unplugging apparatus of that patent included a sensing circuit designed to sense the approach of an electrical storm and thereby activate a solenoid and mechanical actuator to unplug a desired piece of electrical equipment. The sensing circuit of the '042 patent required that a radio frequency coil be tuned to a little used frequency, such that a lightning discharge would cause static to be received at that frequency, which would be sensed by the sensing circuit.
The main problem with the sensing circuit described in the inventor's '042 patent, as well as the remaining prior art, is in the fact that such electronic circuits utilized for the detection of radio frequency disturbances cannot discriminate between damped and undamped wave signals, but rather depend upon the magnitude of the distance to determine a "triggering event". Because prior art sensing circuits cannot discriminate between damped and undamped radio frequency signals, "false triggering" can easily occur at frequent intervals due to other sources of potential static which do not threaten the electrical equipment.